An inflection point in a general sense is a decisive moment in the course of some entity event or situation that marks the start of significant change. The curve and the tangent line intersect see Figure 1. Inflection is related to rate of change of the rate of change or the slope of the slope.
Just to make things confusing you might see them called Points of Inflexion in some books.
In that context an inflection point is a point on a convex upward curve where it becomes concave downward or vice versa. In this example only the first element is a real number so this is the only inflection point. From concave up to concave down or vice versa. Critical points and inflection points 1.